Do you know if the current gas shocks are fully extended out, OR are they sagging, and you can lift the door further?
Posting a pic helps, too, so we can see what you are up against. If you are hitting your head on it, that seems low. By answering the above question, you may determine if the shocks have leaked some gas. If there is more stroke left, as you can lift it higher, then either the gas shocks have leaked out, making them weaker, or they may be slightly undersized from day one.
They do make stronger shocks, and they also make different stroke lengths. I would not remount the existing shock just yet until you sort out what the problem is.
You did not mention if you bought the camper new and this has always done this, or you bought it used and or the door has come down over time. That info also helps.
Hope this helps.
John
